Since Aug. 1, 2016, there have been 457 confirmed cases of hepatitis A in the city of Detroit and Ingham, Lapeer, Livingston, Macomb, Monroe, Oakland, Sanilac, St. Clair, Washtenaw and Wayne counties reported to the Michigan Department of Health and Human Services. That figure represents a 14-fold increase in cases compared to the same period in 2014-15.

Eighteen people have died.

No single source has been identified.

"We are seeing a large person-to-person transmission. It's that not that we have one particular food source, or one specific drug" linking all the cases, said Angela Minicuci, a spokeswoman for the Michigan Department of Health & Human Services.

People affected by the outbreak have ranged in age from 20-87, with a median age of 42, according to the state health department. Most of them, 63%, are men. About 85.6% of the cases involved hospitalizations.

Among men who have sex with men, the hospitalization rate is higher — 95.2% — and the median age is 38.

State health officials said all men who have sex with men should get vaccinated, the same guidance provided by the national Advisory Committee on Immunization Practices.

"Despite this guidance, hepatitis A vaccination coverage among (men who have sex with men) in the United States remains low leaving many adult men unprotected. There are currently multiple hepatitis A outbreaks among (men who have sex with men) in the United States and Western European countries," reads a press release from the state health department.

In the overall outbreak, 48% percent of patients reported illicit drug use, 27.5% were co-infected with hepatitis C, and 3% were co-infected with hepatitis B. Additionally, 6% reported recent incarceration, and 7.7% of men reported having sex with men, according to state health officials.

The state health department has been working with local health departments to investigate cases and raise awareness about the disease and the importance of vaccinations. Those efforts include ongoing vaccination campaigns in the Macomb, Oakland and St. Clair jails, as well as in substance abuse treatment centers and homeless shelters. There are discussions about starting campaigns in the Detroit Receiving Center and the Detroit Detention Center.

Who is at risk

Along with men who have sex with men, the following people are considered at-risk:

• Health care workers who have direct contact with patients
• People who use injection and non-injection illegal drugs
• People who participate in commercial exchange of sexual practices
• People who are homeless or in transient living situations
• People who are or have recently been incarcerated
• People who have had personal contact (e.g., household, sexual) with hepatitis A patients
• Food handlers
• People with liver diseases, such as hepatitis B or hepatitis C.

Health department contacts

For information about receiving a hepatitis A vaccine, contact your local health department: